Well, I see what you're saying and I think you do have a point there, but I guess I am okay with him being an audience proxy because that was the original point of adding Robin to the comic books and I think it adds another dimension to the movie.

I would say Blake's disillusionment "rises" throughout the film. He starts of a bit weary of the Batman/Dent story, because he's a believer in the Batman and the story isn't sitting right. I always took that scene with Gordon as Blake being just as angry that Gordon let Batman, his hero, take the fall as he was that Gordon lied to the city. He knows that Bruce willingly took the blame yet he doesn't reprimand him for it. That's why I always felt he was wrong to judge Gordon so quickly in that scene and don't think he's a character without flaws. He has a huge Batman-bias, because Batman gave him hope when he was young (during a time when Gotham was more corrupt). He's got this hero worship thing going on, and it seems to have affected his very decision to become a cop and how he treats his job as a cop. I think what we see in TDKR is a guy whose naiveté is starting to wear off a little, even at the start of the film. He has questions, but he's not quite ready for the answers.